title: Total mismatch in anterior circulation stroke patients before thrombolysis.
abstract: OBJECTIVE
  Our aim was to estimate the prevalence of negative diffusion-weighted imaging (DWI) with total perfusion-diffusion mismatch in a large series of anterior circulation stroke patients treated with thrombolysis and to describe the characteristics of these patients.
  
  
  METHODS
  From January 2006 to December 2010, a retrospective search was made for total perfusion-diffusion (PWI-DWI) mismatch patterns on pretreatment 1.5-T MRI scans of 166 consecutive thrombolyzed patients taken<4.5 h after onset of anterior stroke. A total mismatch profile corresponded to an absence of initial DWI signal changes with hypoperfusion (T(max)>6 s) on PWI. Clinical and MRI characteristics were compared between DWI+ and DWI- patients.
  
  
  RESULTS
  Five (3%) patients had a normal initial DWI. All had stable substantial clinical deficits (NIHSS scores ≥ 6) and large perfusion abnormalities - in other words, 'total mismatch' - and infarcts in the acutely hypoperfused area on follow-up imaging. While DWI- and DWI+ patients did not significantly differ in any of the pretreatment imaging or clinical variables except for the extent of PWI-DWI mismatch, DWI- patients had lower NIHSS scores at 24 h, and were more likely to show early neurological improvement (Δ0-24 h NIHSS ≥ 8) and good outcomes (mRS ≤ 2) at the time of hospital discharge.
  
  
  CONCLUSIONS
  Total mismatch i.e. failure of DWI to reveal any ischemic tissue despite a large perfusion defect, can be observed before thrombolysis even in stroke patients with stable substantial neurological deficits. However, this rare MRI profile is associated with a favorable outcome after thrombolysis.
authors.affiliation: Inserm UMR 894, department of neuroradiology, centre hospitalier Sainte-Anne, université Paris Descartes, Sorbonne Paris Cité, Paris, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Fustier
authors.forename: Olivier
authors.initials: O
authors.lastname: Naggara
authors.forename: Marie
authors.initials: M
authors.lastname: Tisserand
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Touzé
authors.forename: Charles
authors.initials: C
authors.lastname: Mellerio
authors.forename: Myriam
authors.initials: M
authors.lastname: Edjlali
authors.forename: Caroline
authors.initials: C
authors.lastname: Malherbe
authors.forename: Pauline
authors.initials: P
authors.lastname: Roca
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Baron
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Mas
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Méder
authors.forename: Catherine
authors.initials: C
authors.lastname: Oppenheim
mesh_terms: D000368:Aged; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D002545:Brain Ischemia / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D020521:Stroke / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology*; D015912:Thrombolytic Therapy / Q000379:methods*
keywords: Acute stroke; Diagnosis; Diffusion; Perfusion; Thrombolysis